Spatial and Temporal Distributions of Air Pollutants and Size Distribution of Aerosols over Central and Eastern China

Abstract

The origins and spatial and temporal distributions of air pollutants (PM_2.5, PM₁₀, CO, SO₂, NO₂ and O₃) during May to June of 2015 were investigated using data from 1490 monitoring sites in China. Aerosol number concentrations and meteorological data from Shijiazhuang, Nanjing, and Suzhou were combined with the MIX Asian emission data and the HYSPLIT model. Furthermore, the diurnal variation, size distribution, and main sources of air pollutants and aerosols were selectively characterized in the North China Plain (NCP) and the Yangtze River Delta (YRD). High values of particulate matter concentrations (PM), including PM_2.5 and PM₁₀, occurred in the northwestern and central regions of eastern China. Elevated PM_2.5 and PM₁₀ concentrations represented natural dust sources and anthropogenic resident, power plant, industry, and traffic emissions sources, respectively. The concentrated distributions of SO₂ were similar to those of PM. The CO concentrations were distributed uniformly in China. High O₃ values occurred above the Qinghai province. During the observation period, the air masses mainly originated from the northwest NCP and from the southwest or northeastern ocean in the YRD, resulting in high concentrations of PM_2.5, PM₁₀, SO₂, and CO in the NCP, the average values of which were 61.8 ± 40.0, 118.8 ± 66.4, 24.1 ± 24.6 μg m^-3, and 1.2 ± 0.9 mg m^-3, respectively, and were 1.2, 1.4, 1.5, and 1.3 times larger than those in the YRD. NO₂ had higher concentrations in the YRD with an average of 43.7 ± 24.8 μg m^-3, which was 1.2 times larger than that in the NCP. The diurnal variations of PM, NO₂ and CO had bimodal distributions and SO₂ and O₃ had unimodal distributions in the NCP and YRD. The aerosol number concentrations had average values of 12,661 ± 5266, 11,189 ± 5905, and 12,797 ± 5931 cm^-3 in Shijiazhuang, Nanjing, and Suzhou. Their diurnal variations displayed trimodal peaks at 18:00-21:00, 11:00-14:00, and 06:00-08:00, and their spectra distributions were all unimodal with peaks at 60-70, 60-70, and 100-110 nm, respectively.